1. Field of the Invention
The present invention relates to a gear reduction mechanism, and more particularly to a ball bearing with antiskid design.
2. Description of the Prior Art
Harmonic drive is also called strain wave gearing which is a typical gear reduction mechanism and essentially comprises a wave generator, a flex spline and a circular spline. The wave generator includes an elliptical gear plug and a flexible ball bearing. The flex spline fits over the wave generator and then is disposed inside the circular spline. The elliptical gear plug is connected to a drive force input end. When rotated by the driving force, the elliptical gear plug will push the flex spline and make it partially meshed with the teeth of the circular spline. Therefore, gear reduction can be achieved by the difference of the numbers of the teeth of the flex and circular splines.
When the harmonic drive is working, its transmission accuracy is greatly influenced by the engagement conditions of the respective components. In order to ensure the end transmission accuracy, the harmonic transmission mechanism 10, as shown in FIG. 1, is provided with a friction ring 13 between a driving shaft 11 and a gear plug 12 to reduce ratchet effect and slippage therebetween and improve transmission accuracy.
Another harmonic drive 20 as shown in FIG. 2 is provided with an arc-shaped protrusion 211 around the outer surface of the flexible ball bearing 21 of the wave generator to increase the contact area of the flex spline 22, thus increasing friction and reducing slippage of the flexible ball bearing 21. However, the surface of the flex spline 22 for contacting the outer surface of the flexible ball bearing 21 is flat, therefore, the anti-slippage effect will be limited, and it is unable to completely prevent skid of the flexible ball bearing in the axial direction X.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.